The effect of rare earth elements on the work softening behavior of as-cast Mg-4Al-2Sn

Abstract

This work explores the addition of 1% Rear Earth (RE) elements on the Mg–4Al–2Sn magnesium alloy, with an emphasis laid on the microstructural evolution during solidification and subsequent hot deformation behavior. The morphology of the α-Mg dendrites changes from the butterfly-like (growth at the non-basal planes) to the snow-flake like (growth at the basal planes) due to the addition of RE elements. Dendrite morphology transition (orientation transition) lead to the formation of the various macro-texture at the solidification interval. Subsequently, an appropriate correlation was established between the dendrite orientation selection, solidification texture and deformation behavior of the as-cast microstructure. The workability increases due to the addition of RE elements, which is related to the initial solidification texture and the morphology of the α-Mg dendrites. The results indicated that the dendrites which have snow-flake like morphology in the RE bearing alloys was more favorable for breaking of as-cast microstructure and occurrence of dynamic recrystallization.

Microstructure evaluation and thermal deformation behaviours of wrought magnesium alloys

“…Together with the combined action of dislocation rearrangement around grain boundaries, the arching bend is cut and separated from the original grains and eventually forms new DRX grains, which is called the strain-induced boundary migration (SIBM) nucleation mechanism or discontinuous dynamic recrystallisation (DDRX) [38]. In addition, Nd-and Zn-rich particles near the grain boundary promote the recrystallisation nucleation of DDRX [40]. The dynamic recrystallisation behaviour of the Mg92.2Zn6Nd1Zr0.8 alloy is related to the degree of deformation.…”

The Microstructure of AZ61 with Sm

“…Alloying is an effective way to improve the microstructure and therefore enhance the mechanical properties of magnesium alloy at room and elevated temperatures. The addition of rare earth elements to Mg alloys is an effective way to improve the mechanical properties of alloy [3] . Sm has a unique orthorhombic structure, and can improve the strength of Mg alloys by both precipitation strengthening and solution strengthening mechanisms.…”